The present invention relates to display apparatuses. More particularly, the invention relates to display apparatuses capable of sensing an external input.
Generally, a touch panel may serve an interface between a user and a device that includes a display. The touch panel may receive a direct touch by a finger or a pen as an input. A user may touch the touch panel at a position corresponding to a button shown in a display to operate the device.
Typically, touch panels may be included in various devices, such as portable phones, personal digital assistances (PDAs), information boards, and medical devices.
Touch panels may include capacitive touch panels.
FIG. 5A is a cross-sectional view illustrating a conventional display apparatus 1001 that includes a capacitive touch panel. FIG. 5B is a circuit diagram illustrating equivalent capacitors of the conventional display apparatus 1001 when the conventional display apparatus 1001 is not touched. FIG. 5C is a circuit diagram illustrating equivalent capacitors of the conventional display apparatus 1001 when the conventional display apparatus 1001 is touched.
As illustrated in FIG. 5A, the conventional display apparatus 1001 may include a first substrate 1, a second substrate 2, and a liquid crystal layer 3. The second substrate 2 may include an insulating substrate 21, a black matrix 22, a color filter 23, a first insulating layer 24, a first-type touch line Rx1 (or first touch line Rx1), a second-type touch line Tx1 (or second touch line Tx1), and a second insulating layer 25. One of the substrates 1 and 2 may include a common electrode insulated from the touch lines Rx1 and Tx1. The common electrode may receive a common voltage Vcom.
Only one of the touch lines Rx1 and Tx1 is disposed in a non-display region NA between two pixel regions DA that immediately neighbor each other in the conventional display apparatus 1001.
As illustrated in FIG. 5B, a first common capacitor CR is formed between the first touch line Rx1 and the common electrode, which is applied with the common voltage Vcom. A second common capacitor CT is formed between the second touch line Tx1 and the common electrode, which is applied with the common voltage Vcom. Additionally, an overlapping capacitor CC, an inner capacitor CI, and an outer capacitor CM are formed between the first touch line Rx1 and the second touch line Tx1. The overlapping capacitor CC is formed in a crossing region where the first and second touch lines Rx1 and Tx1 cross each other in a plan view of the conventional display apparatus 1001. The inner capacitor CI is formed within the second substrate 2 by a first touch line Rx1 and a second touch line Tx1 that immediately neighbor each other. The outer capacitor CM is formed outside the second substrate 2 by the first touch line Rx1 and the second touch line Tx1 that immediately neighbor each other. As a width of each of the insulating substrate 21, the black matrix 22, the color filter 23, and the first insulating layer 24 increases, a capacitance of the inner capacitor CI increases, but a capacitance of the outer capacitor CM decreases.
As illustrated in FIG. 5C, a position touched by a user be equivalent to a ground. Since the overlapping capacitor CC and the inner capacitor CI are formed within the display apparatus 1001, they are not influenced by the touch of the user. On the other hand, the outer capacitor CM is influenced by the touch of the user.
When the user touches the display apparatus 1001, the outer capacitor CM is divided into a first outer capacitor CM1 and a second outer capacitor CM2. The first outer capacitor CM1 is formed between the first touch line Rx1 and the ground, and the second outer capacitor CM2 is formed between the second touch line Tx1 and the ground.
The display apparatus 1001 may sense a variation between an equivalent capacitance before the touch and an equivalent capacitance after the touch to confirm whether the display apparatus 1001 is touched or not and to determine coordinates of a touch position.